Evidence for hexadecapole collectivity in closed-shell nuclei

Abstract

Evidence for hexadecapole collectivity in closed-shell nuclei is presented by examining the observed characteristics of the lowest 4+ excited state in each case. These 4+ states, presently identified in the N = 82 isotones Sn and Ce, and the Z = 82 isotopes, Pb and Pb, have nanosecond half-lives, and are found to decay by enhanced E4 transitions to the respective 0+ ground state, whereas AI = 2 E2 transitions from, and to, these states have B(E2) values which are only a fraction of a Weisskopf unit. These features, suggestive of a significant one-phonon hexadecapole component in the structure of these 4+ states, are interpreted in terms of their shell model configurations.Similar characteristics are predicted for some other closed-shell nuclei.PACS number(s): 21.60.Ev, 21.10.Re, 21.60.Cs, 23.20.Lv Low-energy spectroscopic studies of even-even nuclei

Revisiting the island of hexadecapole-deformation nuclei in the A ≈ 150 mass region: focusing on the model application to nuclear shapes and masses

“…Indeed, one can say that, both experimentally and theoretically, it is still interesting and meaningful to further study hexadecapole deformations, especially, based on some new observations (e.g. the low-lying 4 + excited state, indicating the hexadecapole collectivity [69]), in nuclei. ) between theory and experiment.…”

Probes of axial and nonaxial hexadecapole deformation effects in nuclei around 230U

“…A systematic variation of β 4 from positive in the light rare earths to negative in the heavy ones has been revealed [26] through excitation of the ground rotational band by 50 MeV α particles. The evidence for hexadecapole collectivity in closedshell nuclei was presented by examining the observed characteristics of the lowest 4 + excited state [27]. In the lanthanide nuclei, it is found that the β 4 deformation drops from large positive values around +0.1 to large negative values around −0.1 as the mass number A increases from 152 to 180 [25].…”